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The role of metformin on lung cancer survival: the first systematic review and meta-analysis of observational studies and randomized clinical trials

Brancher S, Ribeiro AE, Toporcov TN, Weiderpass E

Journal of cancer research and clinical oncology, 2021

Abstract

PURPOSE: To assess the effects of metformin use on lung cancer (LC) survival according to summarized results from observational studies (OBs) and randomized clinical trials (RCTs).

METHODS: We systematically searched electronic databases and, to our knowledge, for the first time, RCTs were included in a systematic review and meta-analysis about the role of metformin on LC survival. We carried out meta-analyses separately for OBs and RCTs. Analyses for overall survival (OS) concerning OBs were stratified by studies with and without time-dependent approach. Subgroup analyses were adopted for OBs to identify the sources of heterogeneity. Included studies were assessed for quality.

RESULTS: We identified ten OBs and four RCTs. For OBs, metformin use was associated with improved OS for LC patients. Only two studies used time-dependent approach in which a higher ratio was found when compared to the non-use of the time-dependent analysis in eight studies. OBs were classified as high quality but the risk of bias was "unclear" in eight OBs due to absence of the time-dependent analysis. For RCTs, metformin use was not beneficial for OS and neither for progression-free survival. Heterogeneous quality was found among RCTs. Sources of bias that could alter significantly the results or raise doubts were identified in RCTs.

CONCLUSION: Time-dependent analysis should be considered an appropriate strategy for OBs focused on the metformin use for LC patients' survival, and further studies…

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